Maintain Canadian PR while working on H1B in USA

I am a Canadian PR however only spent about 6-8 months after getting PR and then moved to US on H1B in OCT 2014. do you know how much time you need to be in canada to renew this and also i heard that time spent before getting PR also counts, is that true ? My current PR is valid till July 2019.

You have to stay in Canada Physically for at-least 2 years out of 5 years to maintain your Canadian PR.

The 2 years can be on and off like staying in Canada for some time and then coming back to USA.

Does the time spent before obtaining pr status count ? I heard half and maxi upto 2 hears. Is that true ?

I am not sure about the time spent before obtaining PR.

The official guideline says that you should have spent the 2 years out of last 5 years in Canada, at the time of renewing PR.
The renewal date will certainly fall after 5 years of first PR obtaining date.